On the contrary, if a security threat can not be detected, this doesnot necessarily mean that it is inexistent.
The biggest security threat in 2008 was caused by the discovery in May of the Rustock.C, a backdoor Trojan that allows remote attackers to use the compromised computer as an anonymous proxy server. The new backdoor uses advanced rootkit technologies to conceal its files from both the user and from the operating system itself. This means that malicious users can hijack the system without even the user noticing it.
The really interesting part is the fact that the Rustock.C rootkit has been in the wild since October 2007, but it took the industry six months to detect it and issue a fix. Rootkit malware is extremely difficult to remove, even when using specialized tools. It can not be removed by average computer users, so the best solution is installing an anti-virus utility to take care of such security incidents.
In order to control the damage, BitDefender issued an immediate fix for Rustock.C